bit_count.hpp

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#pragma once
 
#include "NumCpp/Core/DtypeInfo.hpp"
#include "NumCpp/Core/Internal/StaticAsserts.hpp"
#include "NumCpp/Core/Internal/StlAlgorithms.hpp"
#include "NumCpp/NdArray.hpp"
 
namespace nc
{
    //============================================================================
    // Method Description:
    template<typename dtype>
    constexpr int bit_count(dtype inValue) noexcept
    {
        STATIC_ASSERT_UNSIGNED_INTEGER(dtype);
 
        int count = 0;
        for (int bit = 0; bit < DtypeInfo<dtype>::bits(); ++bit)
        {
            count += static_cast<int>((inValue & (dtype{ 1 } << bit)) >> bit);
        }
 
        return count;
    }
 
    //============================================================================
    // Method Description:
    template<typename dtype>
    NdArray<int> bit_count(const NdArray<dtype>& inArray)
    {
        NdArray<int> returnArray(inArray.shape());
 
        stl_algorithms::transform(inArray.cbegin(),
                                  inArray.cend(),
                                  returnArray.begin(),
                                  [](dtype inValue) noexcept -> int { return bit_count(inValue); });
 
        return returnArray;
    }
} // namespace nc